Reference : Reassessing the importance of the colour-singlet contributions to direct $J/ + W$ pro...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Physics
http://hdl.handle.net/2268/159188
Reassessing the importance of the colour-singlet contributions to direct $J/ + W$ production at the LHC and the Tevatron
English
Lansberg, Jean-Philippe [Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Physique des astroparticules >]
Lorce, Cédric mailto [Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Physique des astroparticules >]
2013
Physics Letters B
Elsevier Science
B726
218-222
Yes (verified by ORBi)
International
0370-2693
Amsterdam
The Netherlands
[en] We show that the colour-singlet contributions to the hadroproduction of $J/\Psi$ in association with a W boson are sizable, if not dominant over the colour-octet contributions. They are of two kinds, $sg\toJ/\Psi+c+W$ at $\alpha^3s\alpja$ and $q\overline q' \to\gamma^\star /Z ^\star W\to J/\Psi W$ at order $\alpha^3$. These have not been considered in the literature until now. Our conclusion is that the hadroproduction of a $J/\Psi$ in association with a W boson cannot be claimed as a clean probe of the colour-octet mechanism. The rate are small even at the LHC and it will be very delicate to disentangle the colour-octet contributions from the sizable colour-singlet ones and from the possibly large double-parton-scattering contributions. During this analysis, we have also noted that, for reactions such as the production of a $J/\Psi$ by light quark–antiquark fusion, the colour-singlet contribution via an off-shell photon is of the order of the expectation from the colour-octet contribution via an off-shell gluon. This is relevant for inclusive production at low energies close to the threshold. Such an observation also likely extends to other processes naturally involving light-quark annihilation.
http://hdl.handle.net/2268/159188
10.1016/j.physletb.2013.07.059

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